The present invention relates generally to a powder coating booth for coating articles with powder therein and, more particularly, relates to a novel, generally rectangular, powder coating booth which is formed by a plurality of wall elements that can be straightened out to form two flat, spaced, and parallel, walls so that residues of powder can be easily removed from the inner surfaces of the wall elements.
A powder coating booth for coating articles with powder therein is sometimes formed of several wall elements including a left, a right, a front, and a rear wall element and, in addition, a roof. The base of the booth is typically constituted of a movable belt and all the walls of the booth are permeable to air. Articles to be coated are transported in and out of the booth to be sprayed with a powder coating.
In a production environment, it is necessary, at times, to switch from one powder type or color to another. For color integrity and consistency, each powder change-over requires extremely careful and thorough cleaning of the inner surfaces of the walls of the booth of all traces of the previously used powder. The cleaning step disrupts the powder coating process. This is extremely disadvantageous and costly, particularly in mass production environments.
Not surprisingly, persons skilled in the art have been searching for years for the optimal solution that will shorten the switch-over period without adding complexity and cost and a solution that will not compromise the integrity of the cleaning process. The task has not been simple because powder coating quality considerations impose stringent specifications and limitations on the shape and construction of the coating booth. These specifications limit the permissible air current and air quantity levels in the coating booth. The climate in the booth room and the size of the entrance and exit opening through which articles pass into and out of the booth are also subject to stringent requirements. The energy required for maintaining the quality of the air in the booth must also be considered.
The prior art has proposed various solutions for reducing the cleaning time of the booth including a solution that is based on fusing the leftover traces of powder into the walls and roof of the booth, as taught by Federal Republic of Germany Pat. No. 30 12 878.
Another prior art idea is to form the walls and roof of the booth from revolving belts that are operated and cleaned in accordance with the teachings of Federal Republic of Germany Pat. No. 29 26 040.
Swiss Pat. No. 560 558 teaches to form the booth from porous wall and roof parts and to blow air inwardly from outside the booth to prevent accumulation of powder on the inner surfaces of the booth's walls and roof.
A different concept involving providing protective sheetings which are suspended in the booth to protect its inner surfaces is described in Federal Republic of Germany Utility Model No. 78 22 478.
Another prior art concept is based on forming the walls and roof of the booth from filter cloth which can be freed of traces of powder through the blowing of outside air into the interior of the booth room.
Another approach, described in Federal Republic of Germany Offenlegenschrift OS No. 22 48 367, involves creating an electric field on the plastic walls of the booth for repelling the powder away from the walls.
Finally, German Offenlegenschrift OS No. 30 15 929 proposes to form the walls and roof of the booth of easily removable individual panels which are dismantled for cleaning and then reassembled by hand at the conclusion of each cleaning cycle.
However, all of the foregoing solutions are either too complex or otherwise unacceptable because the attained surface cleanliness is inadequate or because the cleaning duration is too long.